Figure 5 shows the average O i \(\) 1304 profile for NGC 5548 during the 1993 HST monitoring. The two narrow absorption lines in the O i profile (see Fig. 4b of [1]}) have been removed, the continuum subtracted, and the spectrum smoothed by a boxcar of half width 1.75 Å. A smoothed H\(\)  profile taken from the simultaneous optical monitoring of [1]} is shown for comparison. This has been scaled by a factor of 0.22. [3]} showed that for NGC 4151, O i \(\) 8446 has the same profile as broad H\(\)  implying that it comes only from the BLR. It can be seen in Figure 5 that the O i \(\) 1304 profile agrees well with the broad H\(\)  profile and clearly lacks a narrow-line region (NLR) contribution. This agreement with the H\(\)  profile is important because there is no sign of Si ii \(\) 1307 emission in the red wing of \(\) 1304. The weaker line on the right-hand side of Figure 5 is the C ii] \(\) 1335 line. Thus, contrary to some suggestions (see Section 3.2), Si ii is not a significant contributor to the \(\) 1304 blend in NGC 5548.
